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lifeonmercury
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If the universe is indeed flat and the cosmological principle holds true, does this mean that there is an infinite amount of space in the universe as well as an infinite amount of matter?
It is expected, based on existing measurements.lifeonmercury said:and believe in the cosmological principle.
And a lot of extrapolation. In Ancient times, by similar reasoning people might think that the Earth is flat and infinite.mfb said:It is expected, based on existing measurements.
nolifeonmercury said:Are there any scientific models that predict a finite, bounded universe (such as one with a center and edges/borders)?
this is nonsenseI recall reading about a theory claiming that the universe is a sphere surrounded by a black hole state at the edges.
No - in this analogy, application of 'cosmological principle' to the surface of the Earth would prompt the ancient people to conclude that the Earth does not have an edge, and instead that the surface is a continuous plane. Either infinite or curved.Demystifier said:And a lot of extrapolation. In Ancient times, by similar reasoning people might think that the Earth is flat and infinite.
This might help:lifeonmercury said:Are there any scientific models that predict a finite, bounded universe (such as one with a center and edges/borders)? I recall reading about a theory claiming that the universe is a sphere surrounded by a black hole state at the edges.
Then you must of necessity believe that the universe cannot be infinite. You MIGHT be right but you can't prove it so that's just a personal opinion, not science.stoomart said:Infinite matter makes as much sense as a singularity of infinite energy.
Agreed, the same is true for both sides of the argument. I think threads discussing infinite time/space/energy are too philosophical in general. It's one thing to say "this is what the math predicts", and another to say "this is what must be": my understanding is the latter is a scarce luxury.phinds said:Then you must of necessity believe that the universe cannot be infinite. You MIGHT be right but you can't prove it so that's just a personal opinion, not science.
I'm not aware of any such. Citations? Our currently accepted model of the universe, the Big Bang Theory, is agnostic on the subject of a creation event.stoomart said:... scientific observation predicts the universe had a beginning ...
I'm not talking about a creation event, I'm referring to the big bang.phinds said:I'm not aware of any such. Citations? Our currently accepted model of the universe, the Big Bang Theory, is agnostic on the subject of a creation event.
Sort of, but only if it is exactly flat and the cosmological principle is exactly true.lifeonmercury said:If the universe is indeed flat and the cosmological principle holds true, does this mean that there is an infinite amount of space in the universe as well as an infinite amount of matter?
stoomart said:I'm not talking about a creation event, I'm referring to the big bang.
Which is exactly what I am talking about. See, the clue was when I said "Our currently accepted model of the universe, the Big Bang Theory"stoomart said:I'm not talking about a creation event, I'm referring to the big bang.
Thanks nikkkom, this is similar to the idea I subscribe to: something along the lines of sequential universes or a multiverse, just not an infinite universe.nikkkom said:Big Bang theory does not say that Universe definitely had a beginning. It merely says that there was a much denser, and much faster expanding state in the past. It is generally understood that before that, "something else" was happening. This "something else" can possibly extend infinitely far into the past. One class of such theories are eternal inflation theories.
Ok sorry, I think the problem is my definition of the universe as the current instance of sequential universes, or a closed system connected to a multiverse.phinds said:Which is exactly what I am talking about. See, the clue was when I said "Our currently accepted model of the universe, the Big Bang Theory"
And that may well in fact be the case BUT ... it is not currently accepted theory (the Big Bang Theory is) and so is not what physicists normally mean by "the universe".stoomart said:Ok sorry, I think the problem is my definition of the universe as the current instance of sequential universes, or a closed system connected to a multiverse.
Is there an FAQ or an accepted source that explains the why physicists accept the universe to be infinite?phinds said:And that may well in fact be the case BUT ... it is not currently accepted theory (the Big Bang Theory is) and so is not what physicists normally mean by "the universe".
That is not what happens. Physicists accept the possibility that the universe could be infinite. We simply do not know today.stoomart said:why physicists accept the universe to be infinite?
As mfb has already pointed out, physicists do NOT accept that as fact. The Big Bang Theory does not posit an infinite universe.stoomart said:Is there an FAQ or an accepted source that explains the why physicists accept the universe to be infinite?
Fair enough, thanks guys.mfb said:That is not what happens. Physicists accept the possibility that the universe could be infinite. We simply do not know today.
An infinite universe is the easiest model that is not in disagreement with observations, but it is not the only one.
The consensus, I believe, is that since we cannot see, and will never be able to see, outside of the Observable universe, we can never know for sure that the universe is infinite. We may be able to say, based on solid evidence, that is almost certainly has to be infinite but we will never know for sure.lifeonmercury said:Is there any consensus about whether it will ever be possible to determine with certainty if the universe is in fact infinite?
stoomart said:Thanks nikkkom, this is similar to the idea I subscribe to: something along the lines of sequential universes or a multiverse, just not an infinite universe.
There is absolutely zero evidence of such a thing.lifeonmercury said:OK, so the idea is that we could never develop good enough technology to see past the cosmic horizon. However, if the universe is actually finite and wrapped around the 4th dimension, would there be some way of proving that (given that we haven't been able to thus far and it may be more difficult to do so in the future due to the continued expansion of space)?
mfb said:Yes.
Edit: Merged another thread into this one.
(1) How do you figure that? I don't get that conclusion at allChrisisC said:But if there is a infinite amount of matter, wouldn't that require new energy to be constantly made forever, violating the law of energy conservation?
Yes, and in fact scientists have looked for evidence of that (repeating structures in the cosmic microwave background). No indication of that has been found.lifeonmercury said:OK, so the idea is that we could never develop good enough technology to see past the cosmic horizon. However, if the universe is actually finite and wrapped around the 4th dimension, would there be some way of proving that (given that we haven't been able to thus far and it may be more difficult to do so in the future due to the continued expansion of space)?
No. There is no need to "make new energy" (this is identical for a finite and an infinite universe), and global conservation of energy does not hold in general relativity anyway.ChrisisC said:But if there is a infinite amount of matter, wouldn't that require new energy to be constantly made forever, violating the law of energy conservation?
phinds said:(1) How do you figure that? I don't get that conclusion at all
(2) Irrespective of whether or not the universe is infinite, "dark energy" is being created constantly
(3) The law of conservation of energy does not apply on cosmological scales.